refactor: VSCode settings を .vscode/ に移行し extensions.json を新設 (#360)

devcontainer.json の customizations.vscode.settings を .vscode/settings.json へ移行。
extensions は devcontainer.json に残しつつ、.vscode/extensions.json も新設。

Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: fjktkm

.devcontainer/devcontainer.json

@@ -8,19 +8,6 @@
 	},
 	"customizations": {
 		"vscode": {
-			"settings": {
-				"files.autoSave": "afterDelay",
-				"editor.formatOnPaste": true,
-				"editor.formatOnSave": true,
-				"editor.formatOnType": true,
-				"files.trimFinalNewlines": true,
-				"files.trimTrailingWhitespace": true,
-				"files.insertFinalNewline": true,
-				"[markdown]": {
-					"editor.defaultFormatter": "esbenp.prettier-vscode",
-					"editor.formatOnSave": true
-				}
-			},
 			"extensions": [
 				"esbenp.prettier-vscode",
 				"tamasfe.even-better-toml"

.vscode/extensions.json

@@ -0,0 +1,6 @@
+{
+	"recommendations": [
+		"esbenp.prettier-vscode",
+		"tamasfe.even-better-toml"
+	]
+}

.vscode/settings.json

@@ -0,0 +1,13 @@
+{
+	"files.autoSave": "afterDelay",
+	"editor.formatOnPaste": true,
+	"editor.formatOnSave": true,
+	"editor.formatOnType": true,
+	"files.trimFinalNewlines": true,
+	"files.trimTrailingWhitespace": true,
+	"files.insertFinalNewline": true,
+	"[markdown]": {
+		"editor.defaultFormatter": "esbenp.prettier-vscode",
+		"editor.formatOnSave": true
+	}
+}